Pathogenesis Of Diabetic Foot Ulcers Research Articles

Autonomic and sensory nerve function in diabetic foot ulceration

Peripheral sensory and autonomic nerve dysfunction are thought to be crucial factors in the pathogenesis of diabetic foot ulceration. However, their relative importance is not known. In this study we have compared peripheral sensory nerve function and cardiac autonomic reflexes in 51 diabetics with a history of foot ulceration and 480 diabetic control subjects. In the diabetics with ulceration ankle reflexes were absent or impaired and vibration perception threshold reduced in 96.1% and 82.4%, respectively, compared with 40.8% and 25.8%, respectively, in control subjects (P less than 0.001). Cardiac autonomic tests were abnormal more frequently in the diabetics with ulceration and an autonomic score derived from four tests was abnormal in 62.8% of those with ulceration compared with 13.5% of those without ulceration (P less than 0.001). Discriminant analysis of the two groups of diabetes showed that an abnormal autonomic score was the best predictor of foot ulceration in diabetic patients.

Abnormal Foot Pressures Alone May not Cause Ulceration

Both rheumatoid arthritis and diabetes have been associated with the development of abnormally high pressures under the feet, and ulceration has been considered to be a problem in both conditions. In order to examine further the relationship between high foot pressure, neurological abnormalities, and ulceration, we have studied two groups of patients: (a) 38 diabetic patients and (b) 37 patients with rheumatoid arthritis who had similar clinical abnormalities of the feet. Thirty-two percent of diabetic patients had a history of plantar ulceration compared with none of the rheumatoid group (p less than 0.01). However, the diabetic group had considerably more severe neuropathy (peroneal nerve motor conduction velocity 35.4 +/- 4.8 m s-1 vs 44.4 +/- 5.2 m s-1 (mean +/- SD), p less than 0.001; vibration perception threshold 33.5 +/- 13.4 vs 16.9 +/- 10.9, p less than 0.001), with a similar frequency of elevated plantar pressures (51% vs 61%, NS). These data emphasize the importance of the loss of sensory awareness in the pathogenesis of diabetic foot ulceration, and suggest that high pressure alone is not a direct cause of ulceration.

The role of autonomic neuropathy in diabetic foot ulceration

In an attempt to define the role of autonomic neuropathy in the pathogenesis of diabetic foot ulcers, we have studied diabetic patients with and without ulcers, and a group of non-diabetic controls. A series of standard autonomic function tests have been compared with measurement of the Galvanic Skin Response (GSR). Patients with foot ulcers showed evidence of more severe somatic and autonomic neuropathy than diabetic subjects with no ulcer. The GSR was found to correlate well with the more conventional tests. In addition it proved to be abnormal more often than any other test for autonomic neuropathy in the diabetic patients with foot ulcers. In a preliminary follow-up study 2 patients with an abnormal GSR but no ulcer at the time of testing have subsequently acquired plantar ulcers. It is suggested that the GSR may prove to be a useful means of detecting diabetic patients at risk from foot ulceration.